How to draw a circle in PHP _php tips

This article illustrates the way PHP draws a circle. Share to everyone for your reference. The implementation methods are as follows:

The basic steps of PHP drawing , there are four steps (php.ini extension = Php_gb2.dll components need to be enabled first)

1, create the canvas;

2, draw the desired image (circle, line, rectangle, fan, arc ...) ）；

3, output to the Web page, or save;

4, destroy the picture (the purpose is to release the memory occupied by the image).

Three most commonly used image formats for Web development: GIF, JPG/JPEG, PNG

(1) GIF format: The highest compression rate, but only 256 colors can be displayed, may cause color loss. Advantages: May display animated images.

(2) Jpg/jpeg format: Compression rate is also relatively high (lossy compression, will also lose some color), the use of more Web pages.

(3) PNG format: Combined with the advantages of GIF and JPG, it cannot display animated images. High fidelity, support lossless compression, the best color preservation, relatively speaking, than Jpg/jpeg to a little bit larger.

PHP Draws a circle with the following code:

Copy Code code as follows:

<?php
1. Create Canvas
$im = Imagecreatetruecolor (300,200);//Create a new true color image, the default background is black, and return the image identifier. Another function, imagecreate, is deprecated.
2, to draw the desired image
$red = Imagecolorallocate ($im, 255,0,0);//Create a color to use
Imageellipse ($im, 30,30,40,40, $red);//Draw a circle. Parameter description: The 30,30 is the center coordinate of the circle, the 40,40 is wide and high, the ellipse is different, and the $red is the circle color (box color)
3. Output image
Header ("Content-type:image/png");
Imagepng ($im);//output to page. If there is a second argument [, $filename], the image is saved
4, destroy the image, free memory
Imagedestroy ($im);
?>

I hope this article will help you with your PHP program design.